I have stayed in a number of hotels around the country recently, and it is a very mixed picture. Most hotels seem to have some sort of track and trace scheme in place, such as requiring contact details for the second person, but how rigidly (if at all) they enforce it is very much up to the hotel and staff on duty.
In London, without all the foreign tourists and coach tours, the hotels are generally very quiet. Once-busy reception areas that you could walk through anonymously are now deserted, with receptionists sitting there twiddling their thumbs - no way will you get in un-noticed. Outside London, hotels seem to be much busier, particularly in areas popular with staycationers.
As others have said, walk in confidently as though you are a guest going back to your room. Helps if you can get some info on where to go, where the lifts are, and so on, as it is not at all obvious in some hotels. If you walk in and obviously haven't got a clue where to go then it will be obvious that you are not a guest, which could raise track-and-trace type questions.
However, the bottom-line is that no WG is going to operate from a hotel where her clients can't get to her.